1. Field of the Invention
The present invention relates to a variable cutting-angle circular saw device which is generally referred to as a miter saw or a compound miter saw.
2. Description of the Related Art
FIG. 5 shows a left-hand side elevational view of a conventional variable cutting-angle circular saw device.
This variable cutting-angle circular saw device is arranged as follows: A rotary table 2 is rotatably disposed in the central portion of a base 1, a hinge 3 is disposed in the rear of the rotary table 2, and a bracket 4 is attached to the hinge 3 in such a manner as to be capable of being lifted and lowered. Fixed to the bracket 4 are a motor 5, a speed reducer 6, a circular saw 7, an outer cover 8, and a safety cover 9. In addition, a fence 10 is fixed in a rearward position of the base 1, and a clamp means 11 is fixed at left- and right-hand positions thereof so as to allow a material (hereinafter referred to as the workpiece) w to be cut, such as timber, to be clamped. The circular saw 7 is lowered until it enters a slit 12 provided in the rotary table 2 so as to cut the workpiece w.
The compound miter saw is arranged such that the rotary table 2 is rotatable to make the miter angle and bevel angle of the circular saw 7 variable, and the hinge 3 is rotatable about a pin shaft 13 within a vertical plane along a transverse direction of the device.
Accordingly, with the compound miter saw, since the circular saw 7 can be inclined with two degrees of freedom, the workpiece w can be cut at virtually any diagonal angle.
With the miter saw, the rotary table 2 is rotatable so as to make the miter angle of the circular saw 7 variable, but the hinge 3 is not rotatable. Accordingly, since the circular saw 7 can be inclined with one degree of freedom, the workpiece w can be cut at an appropriate miter angle with respect to the transverse direction of the device as viewed from its top.
When the circular saw 7 is lowered and the cutting of the workpiece w is commenced, until the circular saw 7 enters the slit 12, the sawdust produced by cutting is blown up in such a manner as to pass by the inner side of the rear end of the outer cover 8 by means of the air flow produced by the rotation of the circular saw 7. The sawdust then passes through a sawdust blow-out port 15 provided in an upper rear end of the outer cover 8, and is discharged to the outside from a sawdust blow-out tube (not shown) provided in such a manner as to pass through an upper portion of the bracket 4. Accordingly, if the sawdust blow-out tube is provided with an air-permeable dust collecting bag, it is possible to collect the sawdust without being scattered. From the time the circular saw 7 is further lowered and begins to enter the slit 12 and until cutting is completed with the circular saw 7 lowered to a position 7', the sawdust passes through the slit 12 and is accommodated in a sawdust accommodating space 14.
Accordingly, the collection of the sawdust accommodated in the sawdust accommodating space 14 becomes an issue.
FIG. 6 illustrates a cross-sectional view taken along the line VI--VI in FIG. 5. The sawdust accommodating space 14 has its four sides surrounded by rib-like vertical walls 2a, 2b elongated in the transverse direction, a front-side inclined wall 2c, and an intermediate inclined wall 2d. An extreme end of the sawdust accommodating space 14 at the rear end of the slit 12 is made open, thereby constituting a sawdust blow-up port 14a.
Returning now to FIG. 5 to resume the description, the fence 10 is arranged such that its central portion corresponding to the circular saw 7 is formed as a curved portion 10a for avoiding interference with the circular saw 7 by detouring the rear side of the sawdust blow-up port 14a, and the wall surface of the curved portion 10a is formed as a conical wall surface 101 disposed in proximity to an edge of the sawdust blow-up port 14a.
Accordingly, when the circular saw 7 is lowered in such a manner as to enter the slit 12, the sawdust accommodated in the sawdust accommodating space 14 is blown up by the air flow caused by the rotation of the circular saw 7, in such a manner as to pass the sawdust blow-up port 14a and pass by the inner side of the rear end of the outer cover 8. Then the sawdust passes through the sawdust discharging blow-out port 15 provided in the upper rear end of the outer cover 8, and is discharged to the outside through the sawdust blow-out tube provided in the bracket 4.
In accordance with the above-described conventional variable cutting-angle circular saw device, since the gap between the lower end of the rear portion of the outer cover 8 and the upper portion of the curved portion 10a in the central portion of the fence 10 is wide open, it does not necessarily follow that the entire volume of the sawdust blown up through the sawdust blow-up port 14a will pass through the gap between the lower end of the rear portion of the outer cover 8 and the upper surface of the curved portion 10a in the central portion of the fence 10. Instead, some of the sawdust will be scattered rearwardly of the device. In addition, during the initial period of cutting when the cutting of the workpiece w is commenced after lowering the circular saw 7, the sawdust is scattered low and rearwardly of the upper surface of the workpiece w. In this case as well, the sawdust passes through the gap between the lower end of the rear portion of the outer cover 8 and the upper surface of the curved portion 10a in the central portion of the fence 10, so that cleaning is troublesome.
Meanwhile, the sawdust accommodating space 14 has its lower portion open owing to the pattern drawing involved in die casting, and communicates with an opening 1a of the base 1. As a result, the dust accommodated in the sawdust accommodating space 14 is discharged to the outside through the gap in the lower surface of the base 1, so that cleaning is troublesome.